The day before, Feinstein announced she would seek a sixth term in 2018. She elaborated on her reasons for running Tuesday, telling donors, who paid $5,400 to attend the event, that her positions on the Judiciary, Intelligence and Appropriations committees put her in a ready position to combat Trump. In the 115th Congress she became the top Democrat on the Senate Judiciary Committee, which is one of the committees probing Russian interference in the 2016 election.

Feinstein said she believes she can harness her intimate knowledge of how government works and the relationships she has built in both parties over a two-decade career in the Senate to give the Democrats a voice as the minority party in the age of Trump.

“Let me be very candid with you. I thought about not doing this,” Feinstein said. “I thought, well, maybe I’ve been there long enough. Maybe I should just walk away. I could actually have a pretty good life, and I’ve worked all my life. Maybe it’s time.”

On NBC’s “Meet the Press” on Sunday, Feinstein was asked whether she would run for re-election. The show’s moderator, Chuck Todd, pointed to a recent poll showing that half of Californians do not want her to run again.

“There are polls and then there are polls. I’m ready for a good fight,” Feinstein said. “I’ve got things to fight for. I’m in a position where I can be effective, and hopefully that means something to California.”

But Feinstein already has the support of a number of key Democrats, including California junior Sen. Kamala Harris.

Inside Elections with Nathan L. Gonzales rates the race Solidly Democratic. Feinstein won re-election in 2012 by 25 points but could face a challenge from within her party in 2018.

Regardless of the pressure from within her party, she said she doesn't plan to change her bipartisan bent.

“It’s my way of working to make whatever we do meaningful,” she said. “You can stand up in this arena … and pound your chest and you don’t get anything done. You need to work with people.”